Lubricating oil additives



Aug. 11, 1970 J. r. GRAGSN- ETAL 3523896 LUBRICATING 0IL: ADDITIVES Filed Aug. 29, 1966 United States Patent 3,523,896 LUBRICATING ()IL ADDTIVES James T. Gragson, David W. Bosse, and King L. Mills,

Bartlesville, kla., assignors to Phillips Petroleum Compauy, a corporatiou of Delaware Filed Aug. 29, 1966, Ser. No. 575,870 Int. Cl. Cm 1/40, 1/10 U.S. Cl. 252-33 7 Claims ABSTRACT OF THE DISCLOSURE A method of increasing the filtration rate of metal sulfonates and overbased metal sulfonates which comprises adding a mixture of methanol and water to the dry sulfonate followed by the heating in the range of 215- 320 F.

This inventon relates to lubricating oil additves. In one aspect the inventon relates to an improved process for the production of metal petroleum sulfonates and overbased metal petroleum sulfonates. In another aspect this inventon relates to a method for increasing the rate of filtration while obtaining an end product contaning a minimal amount of centrifugable solids.

Metal petroleum sulfonates and overbased metal petroleum sulfonates are widely used as additives for lubricating oils in combustion engines. These materals impart detergency to lubricating ol and thus assist in keeping interal engine parts clean and reducing sludge formation in the oil. By increasing the alkaline reserve of the additive, equivalent detergency is obtained with a lower concentration of additive in the lubricating oil. A higher alkaline reserve neutralizes langer quantities of acidic combustion products which accumulate in the oil. The alkaline reserve can be increased by a process which comprises contacting the metal petroleum sulfonates with metal containing materials, a process designated in the art as overbasing.

Alkaline reserve can be measured by a base number which is the number of milligrams of potassium hydroxide equivalent to the amount of acid required to neutralize the alkaline constituents present in a lgram sample. A product having a base number higher than can be 0btained from the compound itself is said to be overbased. The excess of base present in an overbased sulfonate apparently is in the form of very finely divided solid metal compound, particles sufficiently line that they pass through a one micron filter and are not visible to the naked eye. The suspension is stable and does not change on standing. Particles which settle out of the suspension after a period of time can be tolerated only in very small amounts.

In filtering slurries of a metal petroleum sulfonate, it is often necessary that the -filtrate contain, for example, less than 0.1 percent by weight of solids not capable of remaining in suspension under certain conditions of centrifuging. It is desirable to obtain high filtration rates without adding any material which results in solids which will not remain suspended in the metal petroleum sulfonates after centrifuging or otherwise has a deleterious effect upon the product.

It is an object of this inventon to increase the filtration rates of lube ol additives. Another object of this inventon is to increase the rate of production of metal petroleum sulfonates and overbased metal petroleum sulfonates thereby effecting economics in the process while maintaining an acceptable end product. Another object of this inventon is to produce a metal petroleum sulfonate and an overbased metal patroleum sulfonate containing only a negligible amount of solids not capable of remaining in suspension under certain conditions of centrifuging.

Other and further objects of this inventon will be apparent to one skilled in the art upon study of the disclosure and claims of the present application.

According to the inventon, water and methanol are added to stabilized, dehydrated metal petroleum sulfonate and the water and methanol are stripped at a temperature in the range of from 215 to 320 F. and the treated slurry subsequently is filtered. The water and methanol can be added by mxing with metal petroleum sulfonates during slurrying of the material prior to filtration or at ether suitable points prior to filtration. Because the water and methanol which are added in this inventon must be removed at a later stage, it is desirableto introduce the minimum effective amount of water and methanol. At least about 1 weight percent of methanol and at least 0.3 weight percent of water, based on the amount of metal petroleum sulfonate and solids, are added. As indicated above, to obtain most economical operation it is desirable to use no more water and methanol than necessary to obtain the desired effect. Amounts of methanol over about 15 weight percent and water over about 10 weight percent may be uneconomical in many operations. Goed filtration rates are obtained economically by adding trom about 0.4 to 1.0 weight percent of water and 2.5 to 5 weight percent of methanol.

Drying temperatures above 320 F. cause a decrease in filtration rates and promote bleedthrough of solids of a particle size which is not capable of remaining in suspension. The minimum of 215 P. is determined by the fact that at this temperature and above, a substantial portion of the water and methanol can be removed in the dryng step prior to filtration. A preferred range of temperature for drying is from 240 to 300 F.

The inventon is applicable to both non-overbased and to overbased sulfonates. Where the inventon is applied to a process involvng overbasing of the sulfonate, at least a portion of the methanol can be that which is utilized in the overbasing step and at least a portion of the water can be that made during overbasing. By applying this inventon, filter rates are greatly increased, for example, 2% times over the filtration rate necessary to obtain an acceptable amount of centrifugable solids in a conventonal process Where the filter feed is not so treated.

Referring now to the drawng, a suitable lubricating ol .fraction is introduced through line 10 to a sulfonation zone 11 wherein it is contacting with the sulfonating agent introduced through line 12. One suitable lubricating oil fracton is one having a viscosity of at least SUS at 210 F. A preferred fraction is a deasphalted, solventrefined ol having a viscoscity of 140 to 720 SUS at 210 F. Preferably and advantageously, the lubricating ol fraction to be so treated is a propane fractionated, solvent extracted, dewaxed MidContinent ol having a viscosity of 200 to 230 SUS at 210 F. and a viscosity index of 85 to or higher.

Any suitable sulfonation step can be used. In one process, with 20 percent fuming sulfuric acid as a sul fonating agent, the acid-ol ratio can be in the range trom about 0.121 te about 0.721 or even 1:1 to produce the petroleum sulfonates of the inventon. 'l'l1e preferred range of acid-ol ratios for the production of metal petroleum sulfonate is in the range of about 0.3 to 0.6. When the acid-ol ratio is greater than about 1:1, the sulfonate produced is 'black and tarry in contrast to the red, resinons product obtained employing the preferred acid-ol ratios. When S0 in S0 is used as the sulfonating agent, SO -oil weight ratios can be maintained equivalent to those available in the 20 percent fuming sulfuric acid values described above. SO -oil ratios can be controlled by the circulation of SO c0ntaining medium. The sulfonation reaction can be carried out at atmospheric pressure although pressures greater or less than atmospheric can be employed if desired. It is usually preferred to carry out the reaction at suflicient pressure to maintain any S formed in the reaction in solution. The eflluent from the sulfonaton step comprises a petroleum sulfonic acid.

From zone 11 the sulfonated material passes through a line 13 to neutralization zone 14 where it is treated with a neutralizing agent introduced through line 15. The neutralzng agent is an oxide or hydroxide of a basic metal compound. Specific examples of suitable metals are calcium, barium, sodium, lithium, chromium, zinc, nickel, and lead. Good results are obtained with the alkaline earth hydroxides, for example, calcuim hydroxide and barium hydroxide. These materials are introduced in an amount suficient to neutralize the sulfonated material being treated and usually the quantity of the neutralizing agent is substantially in excess of that required for neutralization, for example, 150 percent of the quantity theoretically required. These materials can be diluted with a hydrocarbon introduced through line 16.

The resulting slurry of metal petroleum sulfonate is then passed through line 17 to stabilization zone 18 where the metal petroleum sulfonate is stabilized by heating under pressure as, for example, 350 to 400 F. at 150 to 250 p.s.i.g.

The metal petroleum sulfonate resulting frorn stabilization in zone 18 together with oil, water, and inorganic salts is passed through line 19 to drying zone 20 where the water and some hydrocarbon solvent are removed overhead via line 21. The stabilized, dehydrated metal petroleum sulfonate, often called dryer tower bottoms, are removed via line 22 and, if necessary, diluted with a hydrocarbon solvent, for example, naphtha, via line 23.

The dryer ellluent stream can be passed through line 34 to mixing zone 35 of the overbasing step or can be conducted to dryer-stripper 26 prior to filtration or can be split, one part being the feed stock to the overbasing step, the other part passing directly through line 24 to the drying step prior to filtration. For treating non-overbased product, water and methanol are added through line 25, the slurry of water, methanol, diluent, and metal petroleum sulfonate and solids being transported to the dryng zone 26. The drying temperature is controlled in the range frorn 215 F. to 320 F. Excellent results are obtained at from 240 to 300 F. Substantially all the methanol and water are removed overhead through line 27.

From drying zone 26 the slurry is conducted through line 28 to the filter 29. In the filter, a filter cake is built up on the filter medium which can be filter cloth. Also, the filter medium can be precoated to form an initial layer of solids thereon. A rotary precoat filter is commonly used in a commercial process.

The filtrate from filter 29 passes through line 30 to a stripper 31 where the diluent and traces of methanol and water are removed overhead through line 32 by heating the filtrate in the range from 300 to 350 F. at reduced pressure. After final stripping, the metal petroleum sulfonate product is recovered from unit 31 through line 33.

Metal petroleum sulfonate which is to be overbased flows through line 34 to mixing zone 35 wherein water and methanol are introduced through line 36. Meta] oxide or hydroxide can also be introduced at this point, if needed. After mixing the slurry passes through line 37 to carbonation zone 38 where it is contacted with CO In the embodiment illustrated, the C0 is introduced through line 39 and bubbled through the mixture. The contact with CO can be performed in other ways, as, for example, by contacting in a continuous CO phase or by utilizing compounds which form CO in situ, such as ammonium carbonate, ammonium acid carbonate or ammonium carbamate. The CO -treated slurry is trans- 4 ported through line 40 to dryer 41. Dryer 41 is operated in a temperature range of 215 to 320 F., thereby removing a maximum amount of water and methanol overhead through line 42. The residue is conducted through line 43 to filtration zone 44 where the filtrate is removed through line 45 to stripper 46. In stripper 46 traces of methanol and water are removed overhead through line 47. The overbased product is recovered frorn zone 46 through line 48.

The system illustrated in the drawing can be used to produce only a non-overbased product (valve 49 open, valve 50 closed), only an overbased product (valve 50 open, valve 49 closed), or both non-overbased and overbased products (valves 49 and 50 open). It is also desirable in certain instances to incorporate into the system valves 51, 52, 53, 54, 55 and line 56, which allows the drying, filtration, and stripping equipment to be interchanged and used on either stream.

EXAMPLE 1 A calcium petroleum sulfonate was prepared from a solvent refined, dewaxed lubricating oil fraction derived from Mid-Continent petroleum and having the following properties: viscosity 4278 SUS at F., 203 SUS at 210 F., and a viscosity index of 93. The charge stock identilied as finished 250 stock was sulfonated with liquid S0 in S0 in a continuous operation. The S0 to oil weght ratio was about 0078 and the temperature of the reaction was controlled to F. The total reaction time was 10 minutes including mixing and soaking. The 80; was removed under vacuum and the efiiuent, diluted with naphtha, was run into a vessel containing a calcium hydroxide water slurry for neutralization and the mixture was agitated during the neutralization period. For each 2400 gallons of S0 flash efiiuent, 720 gallons of naphtha was used along with a slurry of 1400 pounds of calcium hydroxide and 1100 gallons of water. The neutralized mixture was then pumped through a 370 F. zone at about 225 p.s.i.g. where its residence time was maintained for about 8 minutes, thus stabilizing the mixture. The stabilized calcium petroleum was then dried at a temperature of 240. The dried product contained calcum petroleum sulfonate, oil, naphtha, excess lime and inorganic salts formed during the neutralization step. This mixture was designated dryer tower bottoms.

In a series of runs, different amounts of water and methanol were added to the dryer tower bottoms to deter mine ther effect on filtration. Each run was dried at 250 F. and filtered. Naphtha was stripped from the filtrates and the amount of centrifugate in the solvent-free cal cium petroleum sulfonate products was determined by the following procedure:

About 8 grams of solvent-free product were accurately weighed into a tared, clean 100-ml. centrifuge tube. Benzene was added to give 100 ml. of solution and the contents were thoroughly mixed. The solution of product and benzene was centrifuged at 2500 rpm. for two hours, then the benzene was decanted leaving the solids in the tube. About 50 ml. of normal pentane was added to the centrifuge tube in a manner to wash the sides free of oil. The solids were dispersed in the pentane and the mixture was centrifuged at 2500 r.p.m. for 10 minutes. The pentane was decanted and the centrifuge tube containing solids was dried at C. for about 15 minutes. The tube was then reweighed and the percent solids was calcu lated according to the formula:

weight of solids Weight of sample 100 solids (weight percent) Wt. percent Dryer tower methanol Wt. percent Drying Filtration Bottoms lbs. added water added temp., F. rato (g.p.h.)

1 Plant dried.

The results of this test show that water and methanol act in combination to give the desired increase in filtration rates.

EXAMPLE II Calcium petroleum sulfonate as was produced in Example I was overbased by addng 2.5 weight percent lime to the dryer tower bottoms containing 27.5 weight percent calciumpetroleum sulfonate and the remainder naphtha and solds. This material was mixed with 3.5 weight percent methanol and contacted with CO The overbased material withdrawn from the bottom of the carbonator was then heated to remove the water and methanol. The drying operation was carried out at different temperatures and at atmospheric pressure. The table below relates the effect of drying temperature to the filterability of the overbased product and to the amount of centrifugable solids in the solvent-tree overbased calcium petroleum sulfonate.

Base number These data show that at drying temperatures of 247 to 3l0 F. excellent filtraton rates were obtained and the weight percent of unsuspended solids in the product was withn acceptable limts. Filtration rates of the product dried withn the range of 247 to 310 F. were approximately double those obtained when the filter feed was dried at higher temperatures, yet the weight percent of unsuspended solids was acceptable.

Other reasonable variations and modifications are possible within the scope of this invention which sets forth a novel method of filtering metal petroleum sulfonates.

That which is claimed is:

1. The method of treating a metal petroleum sulfonate containing sold particles which comprises:

forming a slurry of a calcium petroleum sulfonate of a propane fractionated, solvent extracted, dewaxed Mid-Continent oil having a viscosity of 200 to 230 SUS at 210 F. and a viscosity index of at least 85, unsulfonated oil, naphtha, sold particles comprising excess lime and inorganic salts formed during the neutralization of a sulfonic acid to form said sulfonate, water in an amount in the range of 0.3 to about 10 weight percent, and methanol in an amount in the range of 1 to about 15 weight percent, said weight percents being based on the amount of calcium petroleum sulfonate and solds;

heating the slurry to a temperature in the range of 240 to 300 F. for a time sufficient to remove substantally all of the water and methanol; and

passing the slurry through a filter medium.

2. The method of claim 1 wheren said amount of water is in the range of 0.4 to 1 weight percent and said amount of methanol is in the range of 2.5 to 5 weight percent.

oxide or hydroxide, stabilization and drying, adding to the resulting mixture suflicient Water and methanol to produce the desired concentration in the slurry, and said slurry is passed directly without overbasing to the heating step.

4. The process of claim 1 wheren the slurry also contains calcium oxide or hydroxide and is contacted with CO prior to the heating step thus producing an overbased calcium petroleum sulfonate.

5. The method of claim 1 wheren said calcium petroleum sulfonate is formed by sulfonation of said Mid- Continent oil followed by neutralization with calcium oxide or hydroxide, stabilization and drying, and adding to the resulting mixture suflicient water and methanol to produce the desired concentration in the slurry.

6. The process of claim 5 wheren the slurry also contains calcium oxide or hydroxide and is contacted with CO prior to the heating step thus producing an overbased calcium petroleum sulfonate.

7. The process of claim 1 wheren said temperature is in the range of 247 to 253 F.

References Cited UNITED STATES PATENTS 2,880,173 3/ 1959 Honeycutt 260-504 X 3,006,952 10/ 1961 Logan.

3,027,325 3/ 1962 McMillen et al.

3,111,473 11/1963 Gragson et al. 260-504 X DANIEL E. WYMAN, Primary Examiner I. VAUGHN. Assista nt Examiner 

